求教:邮件经常被退回

bonny

我用的是Magic Winmail Server 邮件服务器软件做邮件服务器,以前使用一切正常,最近总是出现邮件退信:<br>
退信信息如下:<br>
-----Original Message-----<br>
> From: Mail Delivery Subsystem<br>
> [mailto:MAILER-DAEMON@imsantv49.netvigator.com] <br>
> Sent: Friday, December 30, 2005 11:24 AM<br>
> To: admin@smarthero.com.hk<br>
> Subject: Returned mail: see transcript for details<br>
> <br>
> The original message was received at Fri, 30 Dec 2005 11:23:59 +0800<br>
> from imsantv49 [127.0.0.1]<br>
> <br>
> ----- The following addresses had permanent fatal errors -----<br>
> <engineering@smarthero.cn><br>
> (reason: 554 refused 'mail from' because return MX does not exist<br>
> (#5.5.4))<br>
> <br>
> ----- Transcript of session follows -----<br>
> ... while talking to mail.smarthero.cn.:<br>
>>>> MAIL From:<admin@smarthero.com.hk> SIZE=149502<br>
> <<< 554 refused 'mail from' because return MX does not exist (#5.5.4)<br>
> 554 5.0.0 Service unavailable<br>
请教高手,这个问题该怎么解决??